"Use an existing MID Server to connect to a Source Control repository. Linking or importing an application through a MID Server enables access to repositories behind a firewall." https://docs.servicenow.com/bundle
/tokyo-application-development/page/build/applications/concept/c_SourceControlIntegration.html

The Allow configuration Application Access option determines whether users can configure the application tables, such as adding or modifying fields, views, or indexes. The following is true for a table with the Allow configuration option selected:
Out of scope applications can create Business Rules for the table. This is true because the Allow configuration option grants access to the table configuration to any user who has the admin or personalize_dictionary role, regardless of the application scope. This means that users can create Business Rules, which are server-side scripts that run when a record is displayed, inserted, updated, or deleted, for the table from any application.
The following are not true for a table with the Allow configuration option selected:
Only the in scope application's scripts can create Business Rules for the table. This is false because the Allow configuration option does not restrict the creation of Business Rules to the in scope application, as explained above.
Any user with the application's user role can modify the application's scripts. This is false because the Allow configuration option does not grant access to the application scripts, such as client scripts or script includes, to any user who has the application's user role. To modify the application scripts, users need to have the admin role or the application's admin role.
Out of scope applications can add new tables to the scoped application. This is false because the Allow configuration option does not allow out of scope applications to add new tables to the scoped application. To add new tables to a scoped application, users need to have the admin role or the application's admin role and be in the application scope. References: Application Access, Business Rules

It is possible to change an application's scope in ServiceNow, either from global to private or from private to global. However, changing the scope of an application may affect its functionality and compatibility with other applications. Therefore, it is recommended to test the application thoroughly before and after changing its scope.
References:
* How To Change Application Scope In ServiceNow - YouTube
* How to move Custom Scoped Applications bettween instances - ServiceNow
* Steps to switch a scoped application from your company's application repository to update sets - ServiceNow
* How to change the application (scope) of a SLA Definition without needing to recreate the SLA Definition - ServiceNow
* Advantages of Scoped Applications in ServiceNow - QualityClouds

The Event Registry is a table that stores the definitions of all the Events that can be triggered or processed by the ServiceNow system1. The Event Registryallows ServiceNow to react when Events are generated by executing actions such as sending notifications, running scripts, or starting workflows2. The Event Registry also provides information about the Event parameters, description, and source3.
References = 1: Event Registry - ServiceNow Docs 2: Event Management - ServiceNow Docs 3: Event Registry form - ServiceNow Docs

Access Control scripts are server-side scripts that run when an Access Control rule is evaluated. They can use the gs and current objects to access the GlideSystem and GlideRecord methods, respectively. Some of the useful methods in Access Control scripts are:
gs.hasRole() - This method checks if the current user has a specified role. It returns true if the user has the role, and false otherwise. For example, gs.hasRole('admin') will return true if the user is an administrator, and false otherwise.
current.isNewRecord() - This method checks if the current record is a new record that has not been inserted into the database yet. It returns true if the record is new, and false otherwise. For example, current.isNewRecord() will return true if the record is being created, and false if the record is being updated or deleted.
The methods g_user.hasRole() and current.isNew() are not part of the server-side scripting API. They are part of the client-side scripting API, which is used in Client Scripts and UI Policies. They cannot be used in Access Control scripts.
References:
[Access Control scripts]
[GlideSystem methods]
[GlideRecord methods]